PS. 1 - SCIENTIFIC INVESTIGATION

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1 PS. 1 - SCIENTIFIC INVESTIGATION Scientific Method: an organized set of investigative procedures which scientists follow to answer testable questions. Steps include: 1. Identify the problem or question. 2. Gather information (background research). 3. Form a hypothesis (if than ). 4. Test the hypothesis (experiment, qualitative/quantitative observations). 5. Analyze data (create graphs, charts, models as needed). 6. Draw conclusions. 7. Share & repeat the work. Scientific Thinking: - Observing means using your senses/tools to gather information. - Inferring means attempting to interpret or explain what you observe. - Predicting means making a claim about what might happen in the future based on your prior observations (evidence). Scientific Evidence: All scientific claims must be backed up by evidence, or data. Two types of evidence include: Quantitative: Observations that deal with numbers or amounts. Example: The caterpillar has a mass of 10 milligrams. Qualitative: Observations that describe qualities that cannot be expressed numerically. Example: The caterpillar is green. Scientific Research Tips: When doing background research, it is important to evaluate sources. 1. Make sure your research matches your question! 2. Evaluate your sources for: Authority, Accuracy, Objectivity, Currency 3. Use academic sources (.org,.edu,.gov) that are as up-to-date and detailed as possible. Scientific Theory: A well-tested explanation for a natural phenomenon based on many repeated observations and investigations. Examples include; Big Bang Theory, Theory of Evolution, Particle Theory of Matter. Scientific Law: A statement about the natural that always seems to be true, confirmed by repeated observations and investigations. Examples include; Law of Universal Gravitation, Law of Conservation of Matter/Energy, Ohm s Law. Experimental Design: A. Independent variable: the variable that is changed or manipulated by the scientist in order to produce a desired effect. B. Dependent variable: the variable that changes as a result or in response to the changes the scientist makes to the independent variable, is the effect that the scientist measures. C. Constant: a factor that doesn t change in the experiment and is kept the same across all trials.

2 D. Control: a standard by which test results can be compared to normal conditions. E. Repeated trials: necessary to confirm results and reduce the influence of possible errors. F. Validity: a measure of the quality of an experiment a well designed experiment is considered valid and the data collected can be trusted to form a reasonable scientific conclusion. G. Bias: an error in the design of an experiment, which may influence the results, such as changing more than one variable at a time. Ways to avoid: change only ONE variable at a time, repeated trials to confirm results SI Units of Measurement Quantity Definition Instrument(s) Used S. I. Base Unit Symbol Length The distance from one point to another. Meter stick meter m Measuring tape Mass The amount of matter contained in an object or substance. Metric ruler Triple-beam balance or Gram Kg Weight Time The force of gravity acting on an object s mass. The progress of an action (past, present, future). Electronic Balance Spring Scale Newton N Stopwatch seconds S Temperature A measure of the average kinetic energy (amount of motion) in the particles of a substance. Volume of The amount of space a liquid takes up (occupies). Liquid Volume of a Solid The amount of space a solid takes up (occupies). Formula: Thermometer Kelvin Celsius K C Graduated cylinder liter L Metric ruler OR cubic centimeter cm³ Measuring tape Density Length x Width x Height The amount of mass contained in a given volume (mass divided by volume). Formula: Density = Mass Volume Triple beam balance or electronic balance AND Graduated cylinder or measuring tape/ruler grams per cubic centimeter or grams per milliliter g/cm 3 or g/ml

3 Lab Safety Guidelines: 1. Never work unsupervised. a. Do not handle any equipment until instructed. b. Never leave the lab with any equipment or chemicals. c. Report any spills, breakages, or accidents IMMEDIATELY. 2. Wear proper attire and protective equipment. a. Closed toed shoes, hair tied back, lab apron/coat, goggles, gloves. 3. Be careful when handling chemicals. a. Keep chemicals on a level surface below eye level. b. Never smell directly (waft/wave fumes toward you). c. NEVER taste chemicals (or eat/drink while working in the lab). 4. Be careful when heating chemicals. a. Never point the container toward yourself or someone else. b. Always use test tube tongs, heat protective gloves, or oven mitts if you need to pick up a heated container. 5. Maintain an organized laboratory. a. Keep floors and doorways clear at all times. b. Put away all equipment when you are finished. c. Dispose of waste in appropriate containers (trash can, sharps container, liquids container). Safety Symbols 1. Harmful 3. Corrosive 5. Biohazard 4. Danger 2. Explosive 4. Toxic 6. Radioactive 8. Fire Metric Unit Conversion S.I. Prefixes: (largest to smallest): king henry Died by drinking chocolate milk kilo- k thousand 1 km = 1000m hecto- h hundred 1 hm = 100m Deka- Dm ten 1 Dm = 10m Base no prefix one 1 m = 1 m deci- d tenth 1 dm = 0.1 m centi- c hundredth 1 cm = 0.01 m

4 milli- m thousandth 1 mm = m micro- µ millionth 1 µm = m nano- n billionth 1 nm = m 1 st Determine your starting point. 2 nd Count the jumps to your ending point. 3 rd Move the decimal the same number of jumps in the same direction. Scientific Notation: a special way of writing numbers that expresses very large or very small numbers as the product of two numbers a digit term and a power term. If the number is 10 or greater, move the decimal point to the left until the decimal is between the 1 st & 2 nd digits & make the power of 10 positive. Example: 5500 is written 5.5 x 10 3 Because 5500 = 5.5x1000 = 5.5 x 10 3 When the number is smaller than 1, move the decimal point to the right until the decimal is between the 1 st & 2 nd digits & make the power of 10 negative. Example: is written Because = = Data Table Setup: COLLECTING & ANALYZING DATA Title: The Effect of the independent variable on the dependent variable. Column 1 (far left): set values of the independent variable (labeled with units)

5 Column 2 (middle): measured values for dependent variable (label with units include multiple trials) Column 3 (far right): calculated derived quantity (i.e. average, mean, mode, etc.) Example: The Effect of Temperature on Reaction Time for Baking Soda + Vinegar Temperature ( C) Time (s) Average Time (s) Trial 1 Trial 2 Trial Descriptive Statistics: Mean: the average of a group of numbers. 1. Add up all your values. 2. Divide the sum by the number of values. Example: Mean of 7,10,16 = ( ) 3 = 11 Median: the middle number in a set of ordered numbers. 1. Arrange the numbers in order from least to greatest. 2. Find the middle number. 3. If there are two middle numbers, find the mean of these two numbers. Example: Median of 18, 19, 21, 25, 27, 28 = (21+25) 2 = 23 Mode: the number that appears most frequently in a set of numbers. 1. Arrange the numbers in order from least to greatest. 2. Find the number that is repeated the most. Example: Mode of 18, 18, 19, 21, 24 =18 Range: the difference between the greatest and the least value in a set of numbers. 1. Arrange the numbers in order from least to greatest. 2. Find the lowest and highest numbers. 3. Find the difference between these 2 numbers. Example: Range of 18, 19, 21, 24, 27 = = 9 Drawing Conclusions: 1. Look at Column 1 & Column 3 of your data table. 2. Make a statement about what happens to the dependent variable when you change the independent variable. Example: As temperature increases, the average reaction time of baking soda and vinegar decreases. GRAPHING Frequency Distribution: Shows how frequently a value occurs (heights, masses, etc.) occurs within a population, using symbols, tally, or x marks. Bar Graph: Compares categories of data collected by counting, taking averages, etc., using bars that are separated.

6 Pictograph: Compares categories of data collected by counting, using pictures to represent numbers. Histogram: Shows how frequently a value (heights, masses, etc.) occurs over a range within a population, using bars that touch. Line Plot: Shows how frequently a value occurs (heights, masses, etc.) occurs along a number line, using symbols, tally, or x marks. Pie Chart/Circle Graph: Shows fractions, parts of a whole, or percentages as slices of a pie or parts of a circle. Line Graph: Shows a linear relationship (usually change in a particular value height, mass, temperature) over time where the dependent variable changes as a result of the independent variable being changed. *Remember DRY MIX The Dependent (Responding) variable is always graphed on the Y-axis (vertical) and the Manipulated (Independent) variable is graphed on the X-axis (horizontal).* Tips for Interpreting Graphs 1) Determine what the graph represents a. Read any descriptions and try to put them into your own words b. Carefully read axis labels and graph titles to identify variables. 2) Determine which units of measurement that are being used. 3) Look for trends and relationships a. Relationships: i. Direct: when one variable increases (or decreases), the other also increases (or decreases) ii. Indirect: when one variable increases (or decreases), the other one decreases (or increases). b. Trends: i. Positive: Your line slopes upward (both variables increasing). ii. Negative: Your line slopes downward (one variable decreasing while the other increases). iii. No trend: Your line is flat. USING MODELS Scale models: A scale model is a representation or copy of an object that is larger or smaller than actual size. Scale models must maintain relative values of size and/or quantity to maintain the integrity of the object or topic being modeled.

7 Scale models help us: o visualize very small objects. o estimate distance, volume, or quantity. o work out details before making a full size version of something. Examples: House Blueprint, Solar System Mobile, Candy Model of the Cell/Atom. To read a scale model: 1. Look at your scale. 2. Look at your figure 3. Multiply the distances in the figure by the scale number. Conceptual models: Conceptual models provide a way of visually representing abstract concepts or putting events or processes in order. Conceptual models help us illustrate &explain phenomena and systems we can t see. Examples: o The heliocentric (sun centered) model of the solar system is used to explain how the planets move around the sun. o The modern (electron cloud) model of the atom is used to explain how electrons are arranged in atoms. o Food webs are used explain how energy moves through an ecosystem. To read a conceptual model: 1. Think about what you already know about the phenomenon it is representing. 2. Pay attention to any captions, arrows, and relative sizes of objects in the picture. 3. Draw conclusions about the relationships in the picture.